Semi-powered exoskeleton that regulates the muscular activity of jaw movement for oral functional rehabilitation/training

Oral frailty: a concept analysis

BACKGROUND

Oral frailty has become a worldwide problem among older adults. Although researchers have conducted various studies on oral frailty, its definition remains controversial.

PURPOSE

To clarify the concept of oral frailty.

METHODS

Online databases PubMed, Web of Science, CINAHL, Cochrane Library, ProQuest, China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), and Wanfang database were searched from inception to September 20, 2023. The reference lists of relevant studies were searched manually. Eligible articles, theses, and books were analyzed using Walker & Avant's concept analysis model.

RESULTS

The attributes of oral frailty were abnormal oral structure and/or decline in multi-faceted oral function and coexisting decline in physical, cognitive and social functions. Its antecedents were aging, social frailty, and severe periodontitis, whereas its consequences were decline in physical health and mental health, social withdrawal, lower quality of life and systemic frailty.

CONCLUSION

Oral frailty could result in worse conditions among older adults physically, psychologically and socially. Tools based on the concept analysis need to be developed to comprehensively assess oral frailty.

Synchronous Muscle Synergy Evaluation of Jaw Muscle Activities during Chewing at Different Speeds, a Preliminary Study

Human mastication is a complex and rhythmic biomechanical process regulated by the central nervous system (CNS). Muscle synergies are a group of motor primitives that the CNS may combine to simplify motor control in human movement. This study aimed to apply the non-negative matrix factorization approach to examine the coordination of the masticatory muscles on both sides during chewing. Ten healthy individuals were asked to chew gum at different speeds while their muscle activity was measured using surface electromyography of the right and left masseter and temporalis muscles. Regardless of the chewing speed, two main muscle synergies explained most of the muscle activity variation, accounting for over 98% of the changes in muscle patterns (variance accounted for >98%). The first synergy contained the chewing side masseter muscle information, and the second synergy provided information on bilateral temporalis muscles during the jaw closing. Furthermore, there was robust consistency and high degrees of similarity among the sets of muscle synergy information across different rate conditions and participants. These novel findings in healthy participants supported the hypothesis that all participants in various chewing speed conditions apply the same motor control strategies for chewing. Furthermore, these outcomes can be utilized to design rehabilitation approaches such as biofeedback therapy for mastication disorders.

The mouth-opening muscular performance in adults with and without temporomandibular disorders: A systematic review

Background

The mouth‐opening muscular performance in patients with temporomandibular disorders (TMDs) is unclear. Understanding the impairments of this muscle group within specific TMDs is important to develop proper management strategies.

Objective

To characterise the mouth‐opening muscular performance in adults with and without TMDs.

Methods

PubMed, EMBASE, CINAHL, Scopus, Web of Science and Cochrane databases were searched from inception to 12 November 2020. Bibliographies were searched for additional articles, including grey literature. Case‐control, cross‐sectional and interventional studies reporting mouth‐opening muscular strength and/or endurance were included. Risk of bias was assessed by the SIGN checklist for case‐control studies and by the NIH quality assessment tool for cross‐sectional studies. Results were pooled with a random‐effects model. Confidence in cumulative evidence was determined by means of the GRADE guidelines.

Results

Fourteen studies were included; most were rated as having a moderate risk of bias. Only three studies assessed patients with TMDs and the other 11 assessed healthy adults. Significant sex differences in muscular performance were found for healthy adults in the review (strength deficit for females versus males). There was a significant reduction in maximal mouth opening performance (strength and endurance) in the three studies that assessed patients with temporomandibular disorders.

Conclusion

Sex plays a significant role in maximal mouth opening strength. There is a lack of reliable data on the normal mouth‐opening strength and endurance of healthy adults as well as for patients with TMDs.

Implications

Lack of reliable TMDs patient data and comparable healthy adult data highlight future direction for research.

Detection of muscle fatigue caused by repeated posterior tongue lift movement from neck surface EMG: a pilot study

BACKGROUND

Fatigue is an important factor for muscle strengthening in rehabilitation medicine. Frequency analysis has been regarded as the gold standard for muscle fatigue assessment in surface electromyography (EMG). However, there are no experiments quantifying fatigue with grouped discharge (GD), which is one of the historical phenomena observed in patients having fatigue, by using high sampling rate recording of EMG.

OBJECTIVE

To investigate the effect of fatigue, which is induced by repeated posterior tongue lift movement (TLM), on the occurrence of GD peaks, thus, to provide possible basis as a parameter for future fatigue evaluation.

METHODS

Nineteen healthy adults (9 men and 10 women) participated in this study. The muscle fatigue protocol consisted of repetitive posterior TLM and maximum voluntary contractions (MVC). Bilateral N-EMG (Neck surface EMG for measuring the muscle activity of the posterior tongue) was recorded.

RESULTS

Subjective tongue fatigue at the end of the protocol was significantly higher than at beginning throughout the muscle fatigue protocol (p < .01). The frequency of occurrence of GD peaks was 0.9 ± 1.2 (per second) at the baseline in 33 of 38 subject sides, and significantly increased depending on fatigue progression (p < .01).

CONCLUSION

It was shown that fatigue due to repetitive posterior tongue lifting resulted in significant increase in the frequency of occurrence of GD peaks. Especially, the nature of GD, showing very few occurrences at non-fatigue condition, might work as an advantageous property for its use in future absolute evaluation of fatigue phenomena.